This is, so to speak, micro-level. There is also macro-level.

Exercises produces self-confidence, alters self-image and lifts self-esteem. This results in more realistic self-image (less self-delusion and reality distortion) which, in turn, decreases the pain (emotional weariness) caused by cognitive dissonance (when facing reality). This makes you happy.

Go ahead, and tell us where the one ends and the other begins..)